Someone please help me!!!!

Answer:

0.014mol

Explanation:

Given parameters:

Mass of Na₂CO₃  = 1.5g

Unknown:

Number of moles  = ?

Solution:

Number of moles of a compound is mathematically expressed as;

  Number of moles  = [tex]\frac{mass}{molar mass}[/tex]  

 Molar mass of  Na₂CO₃  = 2(23) + 12 + 3(16) = 106g/mol

 Number of moles = [tex]\frac{1.5}{106}[/tex]   = 0.014mol

The normality of the solution which is prepared by dissolving 75 grams of citric acid in water to make 250 ml solution is 4.68 N. Thus, the correct option is C.

Normality is a measure of the concentration of a solution. Normality of a solution is the number of grams equivalent to solute which is present in a given volume of the solution.

Normality of a solution can be calculated by the formula:

N = Gram eq. of solution/ Volume of solution in liters

N = Weight of the solution/ Equivalent weight ×1000/ Volume of solution

N = 75/ 64.4 × 1000/ 250

N = 1.16 × 4

N = 4.64

The normality of the citric acid solution is approximately 4.68 N.

Therefore, the correct option is C.

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Factors that affect the strength of electromagnets are the nature of the core material, strength of the current passing through the core, the number of turns of wire on the core and the shape and size of the core.

Answer:

an effect could be that the battery could be running out of juice or that there isnt enough wire on a nail on the electromagnet.

Explanation:

Answer:

The percent yield would be 73%

Explanation:

The balanced reaction for the obtention of acetylsalicylic acid (aspirin) is the following:

Salicylic acid + acetic anhydride → acetylsalicylic acid + acetic acid

C₇H₆O₃          +          C₄H₆O₃        →         C₉H₈O₄           +    C₂H₄O₂

According to the reaction, 1 mol of salicylic acid reacts with 1 mol of acetic anhydride to give 1 mol of acetylsalicylic acid (aspirin) and 1 mol of acetic acid.

1 mol aspirin (C₉H₈O₄) = (9 x 12 g/mol) + (8 x 1 g/mol) + (4 x 16 g/mol)

                                     = 180 g

1 mol salicylic acid (C₇H₆O₃) = (7 x 12 g/mol) + (6 x 1 g/mol) + (3 x 16 g/mol)

                                              = 138 g

1 mol acetic anhydride (C₄H₆O₃) = (4 x 12 g/mol) + (6 x 1 g/mol) + (3 x 16 g/mol)

                                                      = 102 g

The stoichiometric ratio is = 138 g salicylic acid/102 g acetic anhydride= 1.35

We have:

2.0 g salicylic acid

acetic anhydride = 5.0 mL x 1.08 g/mL = 5.4 g

The reactants ratio is = 2.0 g salicylic acid/5.4 g acetic anhydride = 0.37

0.37 < 1.35 , therefore salicylic acid is the limiting reactant.

Now, we use the amount of salicylic acid to calculate the theoretical amount of aspirin. For this, we know that 1 mol of aspirin (180 g) is obtained from 1 mol of salycilic acid (138 g):

theoretical yield= 180 g aspirin/138 g salycilic acid x 2.0 g salycilic acid = 2.61 g aspirin

actual yield = 1.9 g

Finally, we calculate the yield:

percent yield = actual yield/theoretical yield x 100

        = 1.9 g/2.6 g x 100 = 72.8% ≅ 73%

Answer:

Of the main group elements, fluorine has the highest electronegativity (EN = 4.0) and cesium the lowest (EN = 0.79). This indicates that fluorine has a high tendency to gain electrons from other elements with lower electronegativities.

Explanation:

compound is formed when potassium reacts with chlorine, which forms ions with a negative charge. The formula of this compound would therefore be KCl.

The molecular formula if potassium and chlorine reacted to form a neutral compound will be KCI.

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Answer:

5 moles of iron formed

Explanation:

Given data:

Moles of iron formed = ?

Moles of iron oxide react = 2.50 mol

Solution:

Chemical equation:

Fe₂O₃ + 2Al     →     Al₂O₃ + 2Fe

Now we will compare the moles of iron with iron oxide.

                  Fe₂O₃        :           Fe

                      1             ;            2

                  2.50          :          2×2.50 = 5 mol    

Answer:

Mega = 10^6

Milli = 10^-3

Explanation:

Mega is whatever times 10 to 6th power.

Milli is whatever times 10 to the -3rd power.

Answer:

NaCl may be i guess so....

Answer:

Call 911 then or run away

Explanation:

Answer:

The reaction is 2F_2 (g) + 2H_2 O (g) rightarrow 4HF (g) + O_2 (g) 2 moles of fluorine gas (F_2) reacts with 2 moles of water vapors (H_2 O) to produce 4 moles of hy

Answer:

Their atoms obey the octet rule

Explanation:

Chemical compounds are formed when atoms combine with one another in order to comply with the octet rule. The octet configuration gives an atom stability in electronic structure.

Answer:

The correct answer is 0.020 atm.

Explanation:

Partial pressure is calculated by using the formula,

Partial pressure = Mole fraction × Total pressure

The partial pressure of oxygen in a mixture can be calculated by using the formula,  

Mole fraction of oxygen in mixture = Number of moles of oxygen / No. of moles of oxygen + No. of moles of Helium

(1 gg or gigagram is equal to 10⁹ grams)

= 2 × 10⁹/32 /2 × 10⁹/32 + 98 × 10⁹ / 4

= 2.54 × 10⁻³

Now the partial pressure of oxygen = Mole fraction of oxygen × Total pressure of oxygen

= 2.54 × 10⁻³ × 8.0 atm

= 0.02032 atm

= 0.020 atm

Answer:

4

Explanation:

The Balmer series refers to a series of spectral emission lines of the hydrogen atom arising from electronic transitions from any higher level and terminating at the the energy level n= 2.

Using the relation;

1/λ = 1.09737*10^7 (1/2^2 -1/n^2initial)

We now have;

1/486 *10^-9 = 1.09737*10^7 (1/2^2 -1/n^2initial)

0.1875 = 1/2^2 -1/n^2initial

1/n^2initial = 1/2^2 - 0.1875

1/n^2initial = 0.0625

n^2initial = 16

ninitial = 4

Answer: ?L=250 mL × 1L =0.25L 1000 mL

0.150 M = moles of solute moles of solute = 0.038 mol.

Explanation:

Answer:

Distance measures length. For example, the distance of a road is how long the road is. In the metric system of measurement, the most common units of distance are millimeters, centimeters, meters, and kilometers.

Explanation:

Answer:

c. SP2

Explanation:

The image in the diagram below shows the structure of  NO₃⁻

Nitrogen is the central atom with the electronic configuration of 1s² 2s² 2p³.

So in its outermost shell, it has 3 electrons and the hybridization is sp²

However,

According to Hund's rule:

The ground state of Nitrogen is;    

1s²    2s²   2p³

↑↓     ↑      ↑  ↑  ↑

At the excited state when it is attached to 3 different oxygen ions, we have:

                1s²     2s²        2p⁵

O⁻ --->     ↑↓      ↑↓     ↑↓    ↑↓   ↑      

                1s²     2s²        2p⁵

O⁻ --->     ↑↓      ↑↓     ↑↓    ↑↓   ↑

                1s²     2s²        2p⁴

O⁻ --->     ↑↓      ↑↓     ↑↓    ↑   ↑

Thus, the 3 sp² orbital lies in a plane and form 3 N - O σ- bond and one π- bond.

Answer:

The answer is "Option e"

Explanation:

The ionic bond arousal system of the outer shells (VSEPR) allows us to determine which one of the feasible solutions are found in the majority of instances. It's also supposed to occupy the space with electrical pairs and also to reduce electrical couple repulsive forces to a minimum, its cheapest electricity framework. This theory can be used for predicting a form of electron pairs with a different mass of a particle's core electrons.

Answer:

[tex]7.22 \times 10^{23}e^{-}[/tex]

[tex]1.16 \times 10^{5}C[/tex]

Explanation:

Step 1: Write the reaction for the electrochemical reduction of copper.

Cu²⁺(aq) + 2 e⁻ → Cu(s)

Step 2: Calculate the number of electrons required in the reduction of 0.600 moles of Cu²⁺

We will use the following relationships:

[tex]0.600molCu^{2+} \times \frac{2mole^{-} }{1molCu^{2+} } \times \frac{6.02 \times 10^{23}e^{-} }{1mole^{-}} = 7.22 \times 10^{23}e^{-}[/tex]

Step 3: Calculate the Coulombs corresponding to [tex]7.22 \times 10^{23}e^{-}[/tex]

We will use the following relationships:

[tex]7.22 \times 10^{23}e^{-} \times \frac{1 mol e^{-}}{6.02 \times 10^{23}e^{-}} \times \frac{96486C}{1 mol e^{-}} =1.16 \times 10^{5}C[/tex]

Answer:

C The atoms has a tiny, massive nucleus at its center with electrons surrounding it

Explanation:

From the experiment by Rutherford, he suggested a model of the atom where there is a tiny but massive nucleus at the center with electrons surrounding it.

Answer:

Explanation:

1) Pure substance: Water (found at home)

Appearance: It is homogeneous since it is a single substance that appears as liquid. Homogeneous is when the components of a substance are in a single phase

Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 100 °C

Melting point: Water melts/freezes at 0°C

2) Pure substance: Table salt (found at home)

Appearance: It is also homogeneous as it is a single substance that is solid. Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 1,465 °C

Melting point: Water melts/freezes at 801 °C

3) Pure substance: Butter (found at home and grocery store)

Appearance: It is homogeneous even though it contains different components

Separating technique: It's component can be separated by physical means since butter is an emulsion of fat in water. The 15% water content can be evaporated/distilled out at 100 °C

Boiling point: Butter starts boiling at about 110-120 °C

Melting point: It melts at about 37 °C

4) Pure substance: Candle (wax) (found at home and grocery store)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 370 °C

Melting point: It melts at about 37 °C

5) Pure substance: table sugar/sucrose (found at home, grocery stores and in supermarkets)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 697 °C

Melting point: It melts at about 186 °C

A pure substance is an homogeneous material, having a composition, and

properties that are consistent through out the material.

The chemical properties of a pure substance are defined, such as the

products of its reaction can be predictable.

A chemical is pure when it consist of a single type of particle such as an

element, a molecule or a compound.

The five pure substances are presented as follows;

[tex]\displaystyle\begin{tabular}{|l|l|l|l|l|}\underline{Pure \ Substances}&\underline{Appearance}&\underline{Separaing Tech}&\underline{Boiling \ Point}&\underline{Melting \ point}\\1. Diamond&Translucent \ solid&Inseparable&3550^{\circ}&4830^{\circ}\\2. Table \ salt&White\ crystals&Insepble&801^{\circ}&1413^{\circ}\\3. Water&Tran parent \ liquid&Insepble&0^{\circ}&100^{\circ}\\4. Sugar&Whilte \ crystals&Heating&Decomposes&186^{\circ}\\5. Gold&Yellowish \ metal&Inseparable& 2700^{\circ}&1064^{\circ}\end{array}[/tex]

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Answer:

3)Some gas molecules move further apart and some move closer together.

Explanation:

because When more gas particles enter a container, there is less space for the particles to spread out, and they become compressed. The particles exert more force on the interior volume of the container. This force is called pressure. There are several units used to express pressure.

Answer:

270 mL

Explanation:

First we convert the child's weight to kg:

So the total mass of morphine sulfate that should be injected is:

Finally we calculate the volume that should be injected, using the concentration of the available solution:

The accurate millilitre is 268 mL.

First of all, we must obtain the mass of the child in kilograms;

1 Ib = 0.45 Kg

85 lb = 85 lb × 0.45 Kg/1 Ib

= 38.25 Kg

If 1 Kg takes 35.0 mcg/kg/dose

38.25 Kg takes 38.25 Kg × 35.0 mcg/kg/dose/1 Kg

= 1338.75 mg/dose

Hence;

1338.75 mg/dose/5.0-mg/mL  = 268 mL

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Answer:

[tex]1s^2,2s^2,2p^6,3s^2,3p^6,4s^2,3d^5[/tex]

Explanation:

Hello!

In this case, since electron configurations allows to understand how the electrons in an atoms are arranged depending on the energy levels from 1 to 7 and subshells s, p d and f, considering the attached picture, if we want an element for which the last term in its electrons configuration was 3d⁵, we write:

[tex]1s^2,2s^2,2p^6,3s^2,3p^6,4s^2,3d^5[/tex]

It means that the element has 25 electrons, therefore, it should be manganese.

Best regards!

Answer: it's A the same answer as the dude above me not trying to type all that

Explanation: took the test for ap

Answer:

See explanation

Explanation:

According to Bohr's theory, when external energy is supplied to an atom, its electrons absorb energy and move from a lower energy level to a higher energy level.They quickly return to their original level and re-radiate the absorbed energy as a photo of light.

Hence, when an atom in ground state receives external energy, it becomes excited because energy is transferred to its electrons and they move from lower to higher energy level.

The electron after getting the energy would jump to an orbital further away from the nucleus.  

• Ground state refers to the lowest energy state an atom can be at. When an electron in an atom captivates energy it is considered to be in an excited state.  

• An excited atom becomes unstable and seem to align itself to move back to its lowest energy state.  

• When an atom in its ground state is supplied with an external energy, the energy is absorbed by the atom and the electron becomes excited and jumps to an orbit , that is, distant from the nucleus.  

• It can be said that electron attains higher energy state, with the absorption of more energy by the atom, the electron further moves to higher state till it becomes a free electron and no longer remains the part of the atom.  

Thus, the electron after getting the energy would jump to an orbital further away from the nucleus.

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Answer:

A

Explanation:

Based on the arrows, the direction the air masses are moving is from west

to east.

These contains large volume of air which has a uniform temperature and

humidity. Air masses move in the atmosphere through the process known

as Convection.

The movement of the air tells us that the movement is from  the Western

part to the Eastern part of the atmosphere.

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The coefficient for Br and OH has been 3 and 6 respectively. Thus option C is correct.

If the reaction takes place in a basic medium, the reaction can be given as:

[tex]\rm Br_2\;+\;OH^-\;\rightarrow\;BrO_3^-\;+\;Br\;+H_2O[/tex]

The coefficient has been placed in the chemical reaction to balance the number of atoms on the product and the reactant side.

The number of atoms of Br on the product side has been 2, and the reactant side has been 2.

The oxygen atoms have been 1 on the reactant side, and 3 on the product side.

It has been balanced as:

[tex]\rm 3\;Br_2\;+\;6\;OH^-\;\rightarrow\;BrO_3^-\;+\;5\;Br^-\;+\;3\;H_2O[/tex]

The coefficient for Br and OH has been 3 and 6 respectively. Thus option C is correct.

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Answer:

In the given case, to get a blue flame, one should open the air inlet further. To increase the size of the flame one should open the gas regulator further. When one opens the air inlet, more amount of oxygen goes within, and thus, one can get a more intense form of blue flame.

When one opens the gas regulator more concentration of gas goes and the larger the size of flame one gets.

To regulate a bunsen burner follow this procedure

To get a blue flame, you should rotate the wheel  of the burner anticlockwise further to reduce the level of oxygen flow.

To increase the size of the flame, you should rotate the wheel clockwise further

The bunsen burner is an apparatus in the laboratory used to carry out experiment when heating of substance is required, hence it is used to add heat to substances, it has a wheel used to regulate the flow of air which is required for combustion, it has a hose which is used to tap gas to the burner

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